D.3 Motion in electromagnetic fields Quiz
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5 questions, one answer each
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1. An electron moves parallel to a uniform magnetic field. The magnetic force on it is:
- A. maximum
- B. zero
- C. along the field
- D. opposite to its velocity
2. A proton's speed in a uniform magnetic field is doubled. The radius of its circular path:
- A. halves
- B. stays the same
- C. doubles
- D. quadruples
3. In a velocity selector E = 2.0 × 10⁴ V m⁻¹ and B = 0.10 T. The selected speed is:
- A. 2.0 × 10³ m s⁻¹
- B. 2.0 × 10⁵ m s⁻¹
- C. 2.0 × 10⁴ m s⁻¹
- D. 5.0 × 10⁻⁶ m s⁻¹
4. A 0.50 m wire carries 4.0 A at right angles to a 0.30 T field. The force on it is:
- A. 0.15 N
- B. 0.60 N
- C. 2.4 N
- D. 6.0 N
5. An electron enters a uniform electric field at right angles to the field lines. Which quantity stays constant?
- A. Its speed
- B. Its velocity component perpendicular to the field
- C. Its kinetic energy
- D. Its direction of motion